Original Article
Risk factors for asthma in schoolchildren in Southern Brazil☆

https://doi.org/10.1016/j.aller.2019.07.003Get rights and content

Abstract

Background

Due to the high prevalence of recurrent wheezing in the pediatric population, it is important to be able to identify environmental risk factors that may affect the etiology of asthma in several regions.

Objective

: to identify possible risk factors associated with asthma in children (9–12 years old) in Passo Fundo, Rio Grande do Sul, Brazil.

Material and Methods

A total of 1003 school-age children were selected for the cross-sectional study by applying a standardized written questionnaire from the International Study of Asthma and Allergy, and a supplementary questionnaire (ISAAC phase II) was added to address personal, family and environmental factors. Of these, 125 children were excluded because they did not accept to do the skin prick test, resulting in a sample of 878.

Results

Independent risk factors associated with asthma were bronchiolitis before two years old [OR] = 3.11; 2.23–4.33, current rhinitis [0R] = 2.07; 1.43–3.0; sharing bedroom during the first year of life [OR] = 2.03; 1.36–3.04; atopy [OR] = 1,82; 1.26–2.50; use of paracetamol more than 12 times a year [OR] = 1.68; 1.20–2.31; use of antibiotics in the first six months of life [OR] = 1,57 1;13–2.17; maternal asthma [OR] = 1.75; 1.05–2.78, having an indoor cat during the first year of life [OR] = 1.73, 1.07–2.78; premature birth [OR] = 1.60,1.02–2.50.

Conclusion

our results show that genetic backgrounds, environmental factors, premature birth, use of antibiotics before six months of life, using paracetamol once per month and the presence of co-morbidities such as rhinitis are the risk factors associated with asthma in Brazilian children.

Introduction

Asthma is a global public health issue, affecting people of all ages.1 According to the Global Initiative for Asthma (GINA) summarized data from both ECRHS and ISAAC appeared in the Global Burden of Asthma report. The report highlighted in 2004 the estimation that as many as 300 million people of all ages suffer from asthma. By 2025, it is expected that this number will rise to 400 million worldwide. The increase in the rate of asthma can be explained by the increase in the number of urbanized communities adopting western lifestyle.2

The majority of countries exhibited an increase in the prevalence of asthma at the end of the last century. However, since 2000, the trends have been different. The prevalence of asthma has increased in some countries such as Italy, Sweden and Denmark, mainly between 2010 and 2014. Populations with a higher prevalence of asthma (>20% in children) are in English-speaking countries and in Latin America.1, 2 The prevalence of childhood asthma in Latin America varies substantially (from 4% to 30%) but is above 10% in all the countries.3

Brazil is one of the countries with the highest prevalence of asthma in children, with high rates of severe asthma.4, 5 Between 2002 and 2003, 21 centers in Brazil participated in the ISAAC phase III, comprising 58,144 adolescents aged 13–14 years. The mean prevalence of active asthma in this population was 19.0%, ranging from 11.8% to 30.5%.4 The ISAAC study performed in adolescents (13–14 years old) in Passo Fundo (RS) showed that the prevalence for current asthma was 20.5%.6

Alterations in lifestyle could explain the varying rates of asthma in different communities and its growing prevalence worldwide. Asthma, however, is a multifactorial disorder and of genetic susceptibility, with environmental exposure being one of the parties that collaborate for its development. Although environmental factors are generally well established in some populations and regions, studies in regions of variable prevalence are necessary to confirm these factors and identify the differences among regions.

The aim of this study was to investigate the risk factors that may be associated to asthma in schoolchildren living in Passo Fundo (PF), a medium sized city located in the north of the state of Rio Grande do Sul (RS) - Brazil. It shows a temperate climate and good socioeconomic status, with low infant mortality, comparable to developed countries.

Section snippets

Study population and design

This cross-sectional study was performed in primary schoolchildren in Passo Fundo, located in Southern of Brazil (South latitude 28° 03′ 25″; West longitude 51° 50′ 17); estimated population 200,000 inhabitants [98% in the urban area]; composed by 83% of European immigrants; annual per capita income of approximately US$12,900.00.7 The climate is temperate, annual mean temperature of 17.5 °C, and mean air humidity of 70%.

The target population was students aged nine to 12 (about 14,000) enrolled

Definitions

Current asthma was indicated based on an affirmative answer to the question “Has your child had wheezing or whistling in the chest in the past 12 months?” Active asthma was indicated when it was reported that a child had “Wheezing in the past 12 months plus had asthma ever”. Atopic sensitization was indicated when any of the allergens tested induced wheal with a diameter ≥3 mm after subtraction of the negative control. Infection by geohelminths was indicated when parasitological stool

Statistical analysis

Statistical analysis was performed using program SPSS 18.0 (SPSS Inc. 2009. PASW Statistics for Windows, Version 18.0. Chicago, USA). The differences between proportions were assessed by Chi-square test, or Fisher’s exact test. To measure the magnitude of the effect, odds ratio (OR) and 95% confidence interval (95% CI) from simple and multiple logistic regressions were calculated.

The factors identified by univariate analysis with p < 0.2 were introduced into the analysis of multivariate logistic

Results

The QE and QOL return index was 50.08%, and 878 were submitted to the second phase of the study (TDE, stool parasitological examination, weight and height measures). The prevalence of current asthma was 31.2% and active asthma was 12.4%. Table 1 shows the demography from the total sample (878) that underwent parasitological stool examinations and skin prick tests.

Regarding the prick test, 55.5% of the students were identified as sensitized, regardless of whether they were asthmatic or not (

Discussion

Asthma is a syndrome comprising distinct phenotypes (e.g., atopic vs. non-atopic asthma) and various risk factors. Given the size and diversity of Latin America, it is expected to find a variability in the relative importance of each asthma phenotype and its risk factors. Many urban populations in Latin America present a high prevalence of asthma symptoms in childhood. In addition to that, and in contrast to developed countries, asthma in these populations is less significantly associated with

Conflict of interest

The authors have no conflict of interest to declare.

Acknowledgment

This work was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

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    The authors state that the project was approved by the Research Ethics Committee of UFRGS, protocol n. 12878.

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